1. Field of the Invention
The present invention relates to fat-coated encapsulation compositions in which an active agent or other solid is encapsulated in fat. The present invention also relates to a method for preparing such compositions.
2. Discussion of the Background
The encapsulation of active agents, such as flavorants, is in general well known. Conventional techniques for the encapsulation of active agents include spray drying, melt extrusion, coacervation, and freeze drying.
Encapsulation employing the spray drying process requires that the active agent or encapsulant, in the form of an aqueous emulsion/solution with solubilized carrier solids, be fed into the spray dryer, atomized and dispersed into a heated air chamber plenum, dried, and collected. The resulting product is obtained as a fine particulate with the active agent dispersed within the porous particle matrix either as discrete droplets/particles or essentially dissolved in the matrix. The carrier solutes used in the emulsion preparation are required not only to have emulsifying properties but also be bland, exhibit a high degree of solubility with low intrinsic viscosity, be non-reactive with the flavor load while retaining volatile components, and exhibit stable powder properties once dried. In almost all commercial production formulas the carrier solutes of choice are usually selected for their emulsifying function and high degree of solubility.
It is well known by those skilled in spray drying processes that retention of volatiles is improved with increased dissolved solids levels in the aqueous phase of the emulsion. This requirement generally restricts spray drying encapsulation formulations to the use of highly water-soluble, modified starches, such as the octenylsuccinate-derivatized modified starches, or gum arabic as the emulsifying, film-forming carrier polymer component. Soluble, inert carrier components such as sugars, corn syrup solids and maltodextrins are added to the aqueous flavor emulsion in order to increase the solid level, lower ingredient cost, increase yield, and improve product stability.
The spray drying encapsulation process is relatively simple, economical, and easily scaled to large production volumes. A major benefit of spray drying encapsulation is the broad range of flavors and flavoring systems which can be prepared. These flavorings include oil-soluble flavors, water-soluble compounds, natural extracts, single component flavor compounds, as well as complex compounded flavors having both water- and oil-soluble components.
Yet another technique which has been employed is that of melt extrusion of materials in carbohydrate matrices. In this application, a carbohydrate melt is prepared and the encapsulate is added. The resulting solution is introduced into a quenching medium to produce a solid carbohydrate product containing the flavor. This technique while successful, is again, limited to comparatively high boiling point flavors because the carbohydrate solution is produced and delivered to the quenching medium at elevated temperatures. This technique inherently can result in the loss of some of the low boiling point constituents in the flavor. Because of such losses, it is common to enhance the flavorant by adding extra low-boiling components.
Coacervation encapsulation, a technology commercialized in the 1950s, yields true controlled release functionality and has found wide usage in the pharmaceutical, fragrance and specialty products industries. However the relatively high process costs, sensitive multi-step batch process, regulations limiting the number of polymeric agents which can be used in food preparations, and the difficulty in dealing with encapsulates having both aqueous and lipid solubility properties has drastically limited the application of coacervation for flavor encapsulation in the food industry. A general discussion of these issues is provided by R. Versic, "Coacervation for Flavor Encapsulation," in Flavor Encapsulation, American Chemical Society Symposium Series #370, S. Risch and G. Reneccius, Eds., Chapter 14, 1988, which is incorporated herein by reference.
Coacervation microcapsule systems can be generated in the form of simple coacervates, which are derived from a single polymer species in solution. Complex coacervates, which require the interaction of two distinct and oppositely charged polymer species, are also well characterized.
Freeze-drying solutions of matrix materials containing either dissolved or dispersed flavors has also been used to produce encapsulated flavors. These methods generally result in losses of highly volatile components, and products having a foamy, porous structure.
Spray-chilling is another form of encapsulation practiced commercially. This process begins with mixing a liquid flavor into a molten fat to create a solution/dispersion. The resulting mixture is then atomized into a chamber where it is contacted with an air stream which is cool enough to cause the atomized droplets to solidify, thus forming a crude encapsulated product. The major drawbacks of spray-chilling include fat/active-agent interactions, volatilization over time of lipid soluble materials, as well as loss of volatile materials during processing.
Although all of the conventional encapsulation techniques afford a certain degree of protection to the active agent, in many circumstances it is desired to increase the degree of protection. For example, certain active agents, e.g., vitamins and essential oils, which are sensitive to degradation on exposure to water or the atmosphere may degrade over time even when encapsulated by one of the above-mentioned techniques. Additionally, when encapsulated products are used in final applications, they often must withstand significant environmental challenges.
When it is desired to improve the degree of protection afforded by the above-mentioned encapsulation techniques, the technique of coating the encapsulation composition with a fat coating has been employed. Conventionally, such fat coatings are applied via a fluidized bed technique. This technique suffers from serious shortcomings. For example, exposure of the active agent to a vigorous air stream is one concern when using the fluidized bed technique, as many commercially significant active agents may either volatilize or oxidize under such conditions. This air contacting may occur over a long time period as the rate of fat addition must often be slow, as it is determined by the heat load the air stream can carry away. This also limits the overall productivity of fluid-bed techniques, which in turn influences processing costs and ultimately commercial utility. In addition, the protection afforded by fat coatings applied as described above, or using any method, may be easily lost when the fat-coated particle is exposed to temperatures above the melting point of the fat.
Thus, there remains a need for a method of applying a fat coating to an active agent or other solid which does not suffer from the above-described drawbacks. There also remains a need for fat-coated encapsulation compositions which afford increased protection for the active agent. or solid and for a method of producing such fat-coated encapsulation compositions.